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Biomedical subjects

F Simon

Publications and source records attributed to F Simon.

At least 37 records · Page 2Linked to original sources
PubMed1999

Phylogenetic relationships of the Callitrichinae (Platyrrhini, primates) based on beta2-microglobulin DNA sequences.

The phylogenetic relationships of callitrichine primates have been determined by DNA sequence analyses of exons 1, 2, and 3 of the beta2-microglobulin gene. Parsimony, distance, and maximum likelihood analyses of ca. 900 base pairs of 21 taxa, representing all callitrichine genera, indicated that Saguinus was the most basal offshoot. Within Saguinus, S. fuscicollis appeared as the first divergent lineage followed by an unresolved trichotomy formed by S. mystax/S. imperator, S. midas/S. bicolor, and S. oedipus. A second callitrichine lineage was formed by Leontopithecus; each of the three species studied showed identical nucleotide sequences. Callimico appeared as the sister taxon of Callithrix/Cebuella. Genetic distances within this latter group were very small, although a stronger association between Cebuella and species of the Callithrix argentata group was observed. The inclusion of Cebuella in the genus Callithrix is suggested. These studies indicated that tamarins are more plesiomorphic than marmosets in agreement with the phyletic dwarfism hypothesis.

Animals↗
PubMed1999

Disparate phylogeographic patterns of molecular genetic variation in four closely related South American small cat species.

Tissue specimens from four species of Neotropical small cats (Oncifelis geoffroyi, N = 38; O. guigna, N = 6; Leopardus tigrinus, N = 32; Lynchailurus colocolo, N = 22) collected from throughout their distribution were examined for patterns of DNA sequence variation using three mitochondrial genes, 16S rRNA, ATP8, and NADH-5. Patterns between and among O. guigna and O. geoffroyi individuals were assessed further from size variation at 20 microsatellite loci. Phylogenetic analyses using mitochondrial DNA sequences revealed monophyletic clustering of the four species, plus evidence of natural hybridization between L. tigrinus and L. colocolo in areas of range overlap and discrete population subdivisions reflecting geographical isolation. Several commonly accepted subspecies partitions were affirmed for L. colocolo, but not for O. geoffroyi. The lack of geographical substructure in O. geoffroyi was recapitulated with the microsatellite data, as was the monophyletic clustering of O. guigna and O. geoffroyi individuals. L. tigrinus forms two phylogeographic clusters which correspond to L.t. oncilla (from Costa Rica) and L.t. guttula (from Brazil) and which have mitochondrial DNA (mtDNA) genetic distance estimates comparable to interspecific values between other ocelot lineage species. Using feline-specific calibration rates for mitochondrial DNA mutation rates, we estimated that extant lineages of O. guigna diverged 0.4 million years ago (Ma), compared with 1.7 Ma for L. colocolo, 2.0 Ma for O. geoffroyi, and 3.7 Ma for L. tigrinus.

Alleles↗
PubMed1999

Amplification by atrial natriuretic peptide of the haemodynamic and renal responses to an acute volumic stress in the rat.

1. The purpose of the present study was to test the effects of synthetic atrial natriuretic peptide (ANP) on renal haemodynamics and excretory capacities of salt and water in the rat during an 'acute volumic stress', which was induced by brisk disturbances of the circulatory volume. 2. To this end, 29 anaesthetized male Wistar rats were rapidly injected with 1 mL of 0.85% NaCl, repeated twice at 60 s intervals. The injectates contained no ANP (n = 5) or 1 x 0.25 (n = 6), 3 x 0.25 (n = 6), 1 x 2.5 (n = 6) or 3 x 2.5 micrograms (n = 6) ANP, added to the first injectate only (1 x) or to each injectate (3 x). Renal blood flow (RBF) was continuously measured with an electromagnetic flow transducer. 3. Renal blood flow increased transiently (approximately 30 s) by approximately 13% (P < 0.05) during each injection of saline without ANP. Addition of 0.25 or 2.5 micrograms ANP to the first injectate enhanced RBF by 21 and 35%, respectively (both P < 0.05), but did not modify the time sequence. Furthermore, addition of 0.25 microgram ANP to the second and third injectate produced an almost similar change in RBF at the end of each injection (delta RBF = 20 and 17%, respectively). In contrast, the addition of 2.5 micrograms ANP to the second and third injectate did not produce the same changes in RBF observed at the end of the first injection. The amplitude of the change in RBF was then similar to the increase in RBF induced by 1 mL saline without ANP. Mean arterial pressure (MAP) did not change significantly during repeated injections of saline alone or with addition of 0.25 microgram ANP to the first injectate. However, MAP decreased significantly (by 5, 9 and 9 mmHg) after the injection of 3 x 0.25, 1 x 2.5 or 3 x 2.5 micrograms ANP, respectively. 4. Sodium excretion was rapidly increased from 2.600 +/- 0.654 to 9.330 +/- 1.322 mumol/min after injection of 3 x 1 mL of 0.85% NaCl (P < 0.05). Thereafter, sodium excretion remained enhanced throughout the experiment, so that 70% of the sodium load injected was recovered at the end of the experiment. Atrial natriuretic peptide added to the injectates further elevated the maximal responses in diuresis and natriuresis induced by saline injections without ANP (P < 0.001). A maximal effect was observed after the addition of 2.5 micrograms ANP to the first saline solution. When the amount of sodium excreted was calculated by integrating the areas under the curve of the natriuretic responses, a relationship was established as a function of the amount of ANP added to the saline solutions. It was characterized by a threshold in the presence of 2.5 micrograms ANP added to the first injectate when the integration period was limited to 4 min 30 s and 14 min 30 s after starting the first injection of the varying test solutions. When the integration period was extended until the end of the experiment (2 h), the amount of sodium excreted in each group was further enhanced, especially after injection of 3 x 1 mL of 0.85% NaCl without ANP or with 1 x 0.25 and 3 x 0.25 microgram ANP. Differences in sodium excretion between groups were attenuated (P < 0.054, ANOVA). 5. In conclusion, our results demonstrate differential effects of synthetic ANP on renal vascular reactivity and excretory capacity. These effects were superimposed on changes induced by acute volumic stress. In particular, effects of saline injections on renal vascular compliance were amplified in the presence of ANP added in varying amounts to the injectates. This amplification was limited to 2.5 micrograms ANP.

Animals↗
PubMed1999

Follicle-forming cat thyroid cell lines synthesizing extracellular matrix and basal membrane components: a new tool for the study of thyroidal morphogenesis.

Interactions between follicular epithelial cells and extracellular matrix (ECM) are supposed to play an important role in the development and maintenance of thyroid tissue architecture. In the present study we have therefore investigated the synthesis of ECM components by a feline thyroid cell line which is able to form follicle-like structures in vitro, and also in v-ras-transfected and control-transfected sublines. Transfections were performed by lipofection with pZSR (viral Harvey ras gene; neo) and pSV2-neo (control, neo only) plasmids. We have adapted a semisolid culture system composed exclusively of polymerized alginate and therefore devoid of ECM components. Feline cells embedded in alginate gels as single cells and cultured for up to 90 days formed cell clusters within 10 days. Follicle-like structures were formed in the original cell lines and also in the v-ras- and control-transfected cells. Differences in proliferation rates were observed, the v-ras-transfected cells growing up to two to three times faster than the non-transfected cells. Immunostaining was done using rabbit first antibodies directed against mouse collagen IV, human fibronectin, laminin (tumor Engelbreth-Holm-Swarm laminin), perlecan and other ECM components. For comparison, immunostaining was also performed on cryosections of nodular goiters of six hyperthyroid cats. The cell lines and their transfected clones stained strongly positive for collagen IV and fibronectin, and positively but less strongly for laminin and perlecan. The cat goiter tissue stained positively for collagen IV, laminin, perlecan, and fibronectin, and positive staining for S-laminin (containing the beta2-chain) was seen in blood vessel walls in this tissue. In conclusion, cat cell lines grow three-dimensionally in alginate beads over several weeks, they form follicle-like structures and express the same ECM components as the native cat goiter tissue. Transfection with v-ras does increase proliferation rate, but does not fundamentally alter formation of follicle-like structures and ECM expression. Alginate gel culture is a promising new tool for the study of follicular morphogenesis, polarity, the expression pattern of ECM components and of the interaction between thyrocytes and ECM. It avoids interference caused by gels composed of ECM components.

Alginates↗
PubMed1999

[Ketoconazole].

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Administration, Cutaneous↗
PubMed1999

[Melarsoprol].

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Animals↗
PubMed1998

Genetic characterization of accessory genes from human immunodeficiency virus type 1 group O strains.

Human immunodeficiency virus type 1 (HIV-1) group O strains have been described as highly divergent, compared with the vast majority of the viruses involved in the worldwide AIDS pandemic, classified in group M. To gain new insights into the diversity and genetic characteristics of group O, we have sequenced the accessory gene region (from vif to vpu) of 14 isolates. Analyses of the deduced amino acid sequences for Vif, Vpr, the first exon of Tat, and Vpu indicate that most of the functional domains of these proteins, as described for group M viruses, are highly conserved and retained among all the group O strains we have characterized. The only difference concerns the Vif phosphorylation sites, which are absent in all of the group O isolates we have sequenced; in contrast, they are well conserved in nearly all of the group M isolates, in which they play critical roles in the regulation of viral replication and infectivity. As already observed for group M isolates, the Vpu protein is also highly diverse among group O strains. Phylogenetic analyses of these sequences indicate that HIV-1 group O can be separated into four different clusters, containing most of the strains we have characterized (except one, which clusters outside of the analyzed viruses). Taking into account the criteria used for clades in group M, we were not able to define group O clades definitively.

Amino Acid Sequence↗
PubMed1998

Evaluation of different V3 peptides in an enzyme immunoassay for specific HIV type 1 group O antibody detection.

Strategies to discriminate group O from group M infections need to be improved. We have developed and evaluated an HIV-1 group O V3 peptide-based enzyme immunoassay (PEIA) for specific HIV-1 group O antibody detection among HIV-1-infected patients. Synthetic peptides, derived from the amino acid sequences of the V3 loop of 15 different group O strains and 7 group O consensus sequences, were evaluated in a PEIA against a panel of genetically confirmed group O (n = 33), group M (n = 90), and HIV-1 antibody-negative sera (n = 17). The best-performing PEIA(s) were then used to screen 134 sera of European and 336 sera of Cameroonian origin for the presence of anti-HIV-1 group O antibodies. The reactivity of reference ("gold standard") sera to individual peptides in the PEIA resulted in the selection of five different peptides with sensitivities (sens), specificities (spec), and test efficiencies (TEs) in the range of 90 to 100%. Improvement of the PEIA was obtained with simultaneous reactivity of at least two different peptides in separate wells of an ELISA plate, together with stringent criteria for positivity. We were able to select seven peptide combinations each with a sens, spec, and TE of 96.9, 100, and 99.2%, respectively. None of the 134 European and 4 (1.2%) of the 336 Cameroonian samples sera were group O positive in the optimized HIV-1 group O PEIA; this was confirmed by the repeated presence of reactives, in agreement with the present knowledge of group O infection distribution. Finally, we were able to develop a strategy with a higher TE (99.2%) than the previously used ANT-70 (98.5%) and ANT-70/MVP5180 (95.7%). Our results show that optimal specificity rather than optimal sensitivity makes the V3 PEIA a sufficiently accurate epidemiological tool to be useful in estimating specifically group O infection among HIV-1-infected patients.

Cameroon↗
PubMed1998

HIV type 1 diversity and the reliability of the heteroduplex mobility assay.

We investigated HIV-1 diversity by means of heteroduplex mobility assay (HMA) genotyping. We studied 199 samples from patients originating from 26 countries and living in France. The HMA successfully genotyped 182 (91%) of these samples, as follows: 77 (42%) subtype A, 57 (31%) subtype B, 5 (3%) subtype C, 5 (3%) subtype D, 8 (4%) subtype E, 22 (12%) subtype F, 5 (3%) subtype G, and 3 (2%) subtype H. We were not able to genotype 12 samples by means of the HMA. These latter strains were sequenced, and phylogenetic analyses revealed that they were highly divergent subtype A-, D-, or G-related strains. Eight (of 12) subtype D strains were indeterminate by HMA, owing to the broad intrasubtype diversity, suggesting that new reference subtype D plasmids are required, as previously proposed. Thirty-seven strains belonging to the different subtypes were sequenced, and the results showed perfect concordance with the HMA results. Interlaboratory quality controls confirmed the reliability of the HMA for HIV-1 subtyping, despite the extensive viral variability. However, plasmid selection must be continuously revised to cover viral diversification.

Amino Acid Sequence↗
PubMed1998

HIV-1 diversity in Romania.

OBJECTIVES: To evaluate the prevalence and the dynamics of HIV-1 subtypes in Romanian adults and children, and to investigate the origins of the nosocomial epidemic. DESIGN: A total of 1000 serum and plasma samples, from adults (n = 579) and children (n = 421) who were diagnosed as being HIV-1-infected during 1990-1997 in 39 of the 41 Romanian districts, were serotyped. Viral DNA was isolated from blood samples of 84 patients and the viruses were genotyped. METHODS: Serotyping was performed with a peptide subtype-specific enzyme immunoassay (SSEIA), based on in vitro competition for antibody binding between the representative V3 peptides of the different clades (A-F). Proviral HIV-1 DNA was genotyped by heteroduplex mobility assay or by sequence analysis of the C2-V3 env region. RESULTS: SSEIA showed that 93% of the samples from horizontally infected children were serotype F, 1% were serotype B, and the remaining 6% were uninterpretable. In vertically infected children, 74% of strains were serotype F, 10% were serotype A, 3% were serotype B, and 3% were serotype E. Serotype F was also the dominant subtype in adults (68%), but serotypes A, B, C, D and E were also detected. SSEIA gave indeterminate results in 7% of cases. A strong correlation (90%) between serotyping and genotyping for subtype F was found. Analysis of the relative incidence of the different serotypes over a 7-year period (1990-1997) showed a stable distribution. CONCLUSIONS: Subtype F largely dominates the epidemiology of HIV-1 infection in both children and adults in Romania, although other major subtypes are present. The predominance of subtype F in Romania may be a future potential source of HIV-1 variability in Europe.

Adult↗
PubMed1998

Identification of a new human immunodeficiency virus type 1 distinct from group M and group O.

A highly divergent HIV-1 isolate, designated YBF 30, was obtained in 1995 from a 40-year-old Cameroonian woman with AIDS. Depending on the genes studied, phylogenetic analysis showed that YBF30 branched either with SIVcpz-gab or between SIVcpz-gab and HIV-1 group M. The structural genes and tat, vpr, and nef of YBF30 are approximately equidistant from those of HIV-1 group M and SIVcpz-gab. In contrast, vif and rev are closer to HIV-1 group M, and vpu is highly divergent. Using a YBF30 V3 loop peptide enzyme immunoassay, we screened 700 HIV-1-positive sera collected in Cameroon; three reacted strongly with the YBF30 peptides and one was confirmed as being related to YBF30 by genetic analysis of a pol fragment. YBF30 is as distinct from SIVcpz-gab as it is from HIV-1 group M and can thus be considered as the prototype strain of a new human immunodeficiency virus group.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Alginate gel culture allows the retention of extracellular matrix and follicular structure of rat thyroid tissue but does not lead to the formation of follicles by FRTL-5 cells.

Extracellular matrix (ECM) and basement membrane (BM) components were studied by immunohistological methods in native rat thyroid tissue, and in rat thyroid tissue and FRTL-5 cells cultured in a three-dimensional alginate bead system. In all three situations, the presence of collagen IV, laminin, perlecan, and fibronectin was demonstrated. There were marked differences between rat thyroid tissue and FRTL-5 cells in culture. Rat thyroid tissue maintained a follicular structure, whereas FRTL-5 cells did not form follicles. Rat thyroid cells multiplied more slowly than FRTL-5 cells and thyroglobulin (Tg) was visible in the follicular lumen, while in FRTL-5 cells Tg was only seen intracellularly. Tg iodination was much lower in FRTL-5 cells than in rat cells. In rat thyroid cells, positive staining for collagen IV, laminin, and perlecan was seen in thin membranes around individual follicles, and for fibronectin around groups of follicles. In FRTL-5 cells, these ECM/BM components could be identified, but were not organized into equally regular networks around groups of cells. These results demonstrate that of the two types of cells examined, primary cultures of rat thyroid cells in alginate beads maintain structural and functional similarities to native thyroid tissue and would therefore be suitable for future in vitro studies of thyroidal ECM/BM and their interrelationship with growth and function of this organ. FRTL-5 cells cultured in alginate beads show some functional, but not structural similarities to native thyroid tissue and so would be less valuable for use in such studies.

Alginates↗
PubMed1998

Highly sensitive method for amplification of human immunodeficiency virus type 2 DNA.

We evaluated a new human immunodeficiency virus type 2 (HIV-2) DNA amplification strategy based on peripheral blood mononuclear cell long PCR (XL PCR) followed by nested PCR amplification. The primers used were located in the highly conserved long terminal repeat and in the pol regions of the genome. Five primer pairs corresponding to different regions of the HIV-2 env gene were used in the nested step. Samples from 42 patients were tested, which yielded positive amplification with at least two primer pairs in 40 (95%) samples. A primer pair (EB2/EB5) located on the V3 region succeeded in amplifying proviral DNA in 40 samples.

DNA Primers↗
PubMed1998

Human immunodeficiency virus type 1 subtype F reverse transcriptase sequence and drug susceptibility.

We sequenced and phylogenetically analyzed the reverse transcriptase (RT) regions of the pol genes of 14 human immunodeficiency virus type 1 (HIV-1) isolates from Romanian patients, which were classified as subtype F on the basis of env gene structure. The RT sequences showed that the strains clustered phylogenetically and were equidistant from other HIV-1 subtypes as shown by the neighbor-joining and maximum-likelihood methods, allowing us to define HIV-1 subtype F according to the pol classification. The subtype F RT sequences differed from reported group M RT sequences by 10.94% (for nucleotides) and 7.6% (for amino acids). Phenotypic analysis of subtype F susceptibility to three classes of antiretroviral compounds showed an increase in the 50% inhibitory concentration of the tetrahydroimidazo[4,5,1-jk] [1,4]-benzodiazepin-2-(1H)-one and -thione (TIBO) derivate R82913 for one strain which was naturally resistant to this compound. This first report of subtype F pol sequences confirms the perfect correlation between the phylogenetic positions determined by env and pol analyses and suggests that virus variability might influence the efficacy of antiretroviral treatments. This finding warrants a global evaluation of the phenotypic and genotypic susceptibility of HIV-1 subtypes to antiretroviral drugs.

Adult↗